1. Field of the Invention
The present invention relates to a display device having an organic planarizing film and to an electronic apparatus using the display device.
2. Description of the Related Art
Because of features, such as small thickness and low electrical power consumption, liquid crystal display devices have been used for various types of electronic apparatuses. For example, as the electronic apparatuses each using a liquid crystal display device, a notebook type personal computer, a display device for car navigation system, a personal digital assistant (PDA), a mobile phone, a digital camera, and a video camera may be mentioned.
FIGS. 1A to 1C are views each showing the structure of a general liquid crystal display device, FIG. 1A is a cross-sectional view of a device structure, FIG. 1B is a plan view of a TFT substrate side taken along the line I-I in FIG. 1A, and FIG. 1C is a plan view of a counter substrate side taken along the same line as described above.
A liquid crystal display device 1 includes an array substrate (substrate on which active elements are formed) 2, a transparent counter substrate 3 disposed to face the array substrate 2, and a liquid crystal layer 4 disposed between the above two substrates 2 and 3.
Pixels including transparent electrodes (pixel electrodes) 21 for applying a voltage to a liquid crystal and thin film transistors (TFTs) 22 for selecting the transparent electrodes 21 are disposed in a matrix on the array substrate 2, so that a pixel area PXLA is formed.
In addition, in order to reduce steps formed on the thin film transistors, a planarizing film 23 is provided between the transparent electrodes 21 and the thin film transistors 22 provided on the array substrate 2.
On the counter substrate 3, a color filter portion 31 composed of black (BK), red (R), green (G), blue (B), and the like which correspond to pixels PXLs on the array substrate 2 is formed, and in order to reduce steps formed on the color filter portion 31, a planarizing film 32 composed of an organic film is also formed.
A transparent electrode 33 is formed on the planarizing film 32 at the side facing the liquid crystal layer 4 for applying a voltage to a liquid crystal.
In addition, in order to fix the array substrate 2 and the counter substrate 3 and to enclose the liquid crystal therebetween, a sealing area 5 is formed so as to surround the pixel area PXLA in which the pixels PXL are formed.
As described above, in the general liquid crystal display device 1, constituent elements, such as metal wires 24 including array drive terminals, the transistors 22, and the transparent electrodes (transparent conductive films) 21, are disposed on the array substrate 2 which is one of the substrates facing each other. In addition, constituent elements, such as a color filter displaying colors, are disposed on the counter substrate 3.
In addition, since steps are formed on each surface closest to the liquid crystal layer 4 due to the presence of the constituent elements described above, the distance in the plane of the liquid crystal between the above two substrates is changed, so that image quality, such as contrast, is degraded by the deviation in liquid crystal optical properties which occurs between the pixels and/or in the pixels.
In order to prevent the above problem, planarizing films each composed of an organic film are provided at the substrate sides so as to planarize the steps caused by the wires and the like.
In addition, when the organic film is extended outside past the sealing area which is formed to fix the two substrates of the liquid crystal display device and to enclose the liquid crystal, the in-plane uniformity of optical properties of the liquid crystal display device can be improved.
In addition, in order to ensure a wide viewing angle of a liquid crystal display device, various liquid crystal display devices using a fringe field switching (hereinafter referred to as “FFS”) method have been proposed (see Japanese Unexamined Patent Application Publication Nos. 2002-229032 and 2001-42366).
In a liquid crystal display device having a fringe field switching (FSS) structure, a counter transparent electrode is not disposed at a counter substrate side but is disposed at an array substrate side.
In particular, a counter electrode (common electrode) is formed on a planarizing film composed of an organic film at the array substrate side, a pixel insulating film (SiO2, SiN, or the like) is formed on this counter electrode, and pixel electrodes (transparent electrodes) composed, for example, of ITO are formed on this pixel insulating film at the side of an interface with a liquid crystal layer.